: Good for those who want the option of online ordering with local pickup.

: Before buying, search for the medication on GoodRx for Pets to compare prices across different pharmacies.

Most reputable pet pharmacies will contact your vet directly to verify the prescription during checkout.

: Your vet must test your dog for existing heartworms before writing the prescription, as giving the preventative to an infected dog can be dangerous.

Buying Sentinel for dogs online requires a valid prescription from your veterinarian, as it is an FDA-regulated heartworm preventative. Reliable Online Retailers

: A licensed pharmacy frequently offering competitive prices and "AutoShip" discounts.

: Ensure you select the correct box color based on your dog's current weight (e.g., Yellow for 26–50 lbs, Blue/White for 51–100 lbs).